Molecular arrays have been successfully used to perform analytical assays. Such arrays may be used for detection of antibody recognition, analysis of nucleic acid molecules, peptide detection, drug screening, genetic typing and fingerprinting, and disease diagnosis.
Typically, an array contains binding molecules of several disparate species of a single type or class of molecule (e.g., DNA, or protein), each species being placed on one or more points, or features, on an array. Analytes, such as those found in a DNA sample, are usually washed over the entire array in a liquid medium. Analytes bind to specific features in the array because of specific interactions between the analytes and binding molecules. Examples of such specific interactions include, but are not limited to, antibody-antigen interactions, sequence specific nucleic acid binding, ligand-receptor interactions, and binding protein-nucleic acid interactions.
When an analyte is bound to a specific feature of an array, the presence of the analyte is typically indicated by a fluorescent molecule. The fluorescent molecule is either attached to the analyte prior to washing over the array, or it is attached afterwards. The result is that fluorescent molecules are immobilized on those features on the array where binding of an analyte has occurred.
Fluorescent molecules typically absorb light of a specific wavelength, then emit light at a second wavelength. Detection of light of this second wavelength from a feature on an array indicates the presence of the analyte.